1. Field of the Invention
The present invention relates to a method of and system for incinerating sludge.
2. Description of the Prior Art
Sludge is generally composed of minute particles and hence would not allow air to circulate through the inter-particle spaces during combustion, causing inefficient and non-uniform incineration. To facilitate incineiation, it has been a common practice that an amount of air, ranging from two to two and a half times as much as a theoretical amount of air needed to combustion of the sludge, is blown for the sludge while the latter is stirred in the incinerator. However, in this conventional method, when such large amount of air is blown to it, the sludge would be burned suddenly so that the temperature of parts of the sludge increases to over 1,200.degree. C. As a result, clinker would be produced in the incinerator; clinker is in the form of very hard lumps of ashes which not only are difficult to be burned up, but also retard the combustion of the remaining sludge, thus causing inefficient incineration and non-stable operation of the incinerator.
Otherwise, if a reduced amount of air were supplied into the incinerator in an attempt to minimize the production of clinker, the incinerator would be rather much more overheated due to insufficient cooling ability by air and, as a result, there would be a danger that clinker is developed all over the bottom of the incinerator in stead of being minimized. In this condition, stable operation of the incinerator for a long time is difficult to achieve.